Method of making socket-caps



A. W. LIMONT. METHOD OF MAKING SOCKET CAPS.

APPLICATION HLED FEB. 10. 19-15 Patented Feb. 15, 1921.

2 SHEETS-SHEET l- [NVF/VTOA QM. 68M) mt} m WITNESSES A. W. LLMONT.

OOOOOOOOOOOOOOOOOOOOOOO S.

ALEXANDER W. LIMONT, 0F BRIDGEPORT, CONNECTICUT, ASSIGNOR TO BRIDGEPORT BRASS COMPANY, OF BRIDGEPORT, CONNECTICUT, A CORPORATION OF CON- METHOD OF MAKING SOCKET-CABS.

Specification of Letters Patent.

Patented Feb. 15,1921.

Application filed February 10, 1915. Serial No. 7,291.

To all whom it may concern Be it known that I, ALEXANDER W. MONT, a citizen of the United States, residing in Bridgeport, county of Fairfield, and State of Connecticut, have invented certain new and useful Improvements in Methods of Making Socket-Caps, of which the following is a full, clear, and exact description.

This invention relates to the metal caps of electric light sockets or shells, which are commonly known as socket caps. As ordinarily constructed, these caps consist of at least three separate parts, to wit: a shell or cap proper constructed of light sheet metal; a relatively heavy hub or bushing, having a threaded bore; and a washer, by means of which the hub is clenched or staked to the shell. This construction, however, has the drawback that notwithstanding the exercise of considerable care, it will usually be found that of a given number of caps manufactured by the customary operations, some are defective owing to the looseness of the connection between the hub and the shell. Then again, even if the hubs are tightly locked to the shells when the articles leave the factory, the parts are very apt to work loose if they are subjected to slight strains. Furthermore, with the ordinary construction, the shell itself is quite weak at or near the juncture with the hub or bushing, and this causes the shell to crack when it is subjected to a comparatively slight strain.

One of the objects-of my invention is to provide a method of making socket caps in which the above-mentioned defects are eliminated. Another object of the invention is to furnish a simple and efficient socket cap in which the shell and hub are integral with each other, being stamped from a single metal blank, and wherein, nevertheless, the hub has a wall of sufiicient thickness to carry a cut thread without buckling under the stresses to which it is subjected. Furthermore, in accordance with my invention, the entire shell orcap proper may be made from the same piece of metal-as the hub and it may be so designed as to combine maxi mum lightness with maximum resistance against cracking or splitting at the zone of special strain.

Another object of the invention is to furnish a very practical and economical method by which socket caps of the kind above mentioned may be produced commercially in a satisfactory manner.

To these and other ends, the invention consists in the novel features and steps to be hereinafter described and claimed.

1n the accompanying drawing,

Figure 1 is a perspective view of a socket cap constructed in accordance with my in vention.

Fig. 2 is a vertical section of the cap.

Fig. 3 is a detail of the blank. I

Figs. 4 to 8 inclusive show the blank at different stages in the process of manufaodture; Figs. 4 4 and 4 show details; an

Fig. 9 shows one stage in a somewhat modified process of manufacture.

Referring particularly to Figs. 1 and 2, my improved socket cap comprises a domeshaped shell. 10 of sheet or wrought metal, and a hub or bushing 11 integral therewith, at the summit of the dome and having a bore provided with interior screw threads 12. At its free edge, periphery or rim the shell is usually provided with the flange or offset 13 which is formed as an integral part there of. In the particular form shown, the wall of the hub 11 is quite thick relative to that of the shell and the threads 12 are cut in the wall of the hub, or in other words, they are formed by the usual tapping operation. At and near its juncture 14 with the hub, the wall of the shell is thicker than at the pe ripheral portion of the shell so as to reinforce the line or Zone of juncture and make it thick and strong enough to resist the strains to which it is subjected. In the particular example illustrated, the cross-sectional area of the shell wall is progressively increased from the rim to the juncture with the hub. In the ordinary use of the device, the rim portion is subjected to much less strain than the juncture between the shell and hub and it will be apparent that my construction meets this condition in a very effective way.

A clearer understandingof the construction of the particular cap illustrated may perhaps be had. from a description of the method by which the article is manufactured. I take ailat disk 15 of brass or other a. shallow, gradually curved cup or boss 18 and the cross-section. of the bottom of the cup or boss is somewhat reduced as compared to the initial cross-section. The blank is then transferred to a die 19, as shown in Fig. 5, and is formed by means of a punch 20 cooperating with said die. The die 19 is provided with a depression or recess 19 of less diameter than the blank resulting from theoperation shown in Fig. l, and this depression or recess 19 has a substantially fiat bottom and an upright, substantially cylindrical side wall. The punch 20 carries a projection 20 adapted to enter the recess 19 with a considerable amount of clearance at the periphery of the recess, and surrounding the recess 19" is a flat stamping surface 19 on the die adapted to cooperate with a similar flat stamping surface 2O on the punch surrounding the projection 20 When the blank resulting from the operation shown in Fig. 4 is formed by the punch and die shown in Fig. 5, a substantially cylindrical boss 21 of relatively small diameter is formed on the blank. The'blank then has the peculiar characteristic that the side wall'of the boss 21 formed by this operation is thicker than any other part of the blank, that is, the cross-section area of said wall is greater than that of the flat outer or brim portion of the blank and greater than the cross-section of the bottom of the boss 21. The substantially cylindrical wall of the boss 21 preferably approximates the original blank in thickness. At the same time, the flat outer port-ion of the blank is made very much thinner than the original blank. As the punch 20 descends on the blank resulting from the operation shown in Fig. 4c, the outer or peripheral portion of the blank is swaged or flattened out considerably by the cooperating surfaces l9", 20 of the die and punch, but nevertheless, while the unconfined outer peripheral portion is being forced out laterally to thin the same and increase the'diameter of the blank, that portion of the punch surrounding the projection 20 forces or displaces the adjacent metal inward and down into the recess 19 to form the thick wall2l' previously mentioned. To accomplish this end, the punch projection 20* joins the stamping surface .20 on an easy curve or fillet and the dieis shaped correspondingly. Furthermore, at the same time that the. punch is forcing metal inwardly and downwardly into the recess 1 to form the thick wall 21., said punch is also 31611 metal upwardly into the wall fZl from the bottom of the boss. This isaccomplished by designing the punch and die so that when the punch. is moved to its lowest position, the lower surface of the projection 20 presses veryforcibly the met-albetween it and the bottom of the recess 19 so as to flow or displace such metal outwardly in a radial direction and upwardly around the side surface of the projection 20 Figs. 4*, r and 4: show, on a larger scale certain stages of the operation intermediate those shown in Figs. l and 5. Fig. 4 shows the members 20 and 19 just closing on the blank; Fig. 4: shows a later stage in theforming up of the boss and the thinning out of the peripheral portion; and Fig. a shows a stage immediately preceding that of Fig. 5, wherein, certain voids subsequently filled up are present at the top and bottom of the central boss. The metal at the outer peripheral portion of the blank being unconfined at the margin of the blank is flowed outwardly, but at that part where the side wall of the boss or wall 21 joins the brim portion there is great resistance to outward move ment, owing to surface friction, and the metal, taking the path of least resistance, moves inwardly to fill the void at the base of the boss, whichthickens up the wall of the boss at that place.

It will be understood, thereforegthat the operation shown in Figs. 4 4 4 and 5 consists of flattening out and thinning the outer or peripheral part of the blank shown in Fig. l, thereby increasing the diameter of the blank; and in forming at the center portion of the blank a boss having a thick side wall, by flowing or displacing metal outwardly and upwardly from a'zon'e at and near the center of the blank, and flowing or displacing inwardly and downwardly a certain amount of metal located in another zone more remote from the center of the blank.

After the forming operation shown in Fig. 5 is completed, the blank has its fiat. brim further thinned out as shown in Fig. 6 without, however, materially changing the shape of the boss 21. This may be effected by placing theblank in a die similar to the die 19 and using a punch similar to the punch 20, but having a. centering projection of less depth than the projection 20. In this operation one or more sharp quick, hammer-like blows of the punch are required. The blank shown in G is then subjected to the cupping operation ,Jliown in. F g. 7 for the purpose of shaping the flat brim portion into a dome-shaped shell. For this purpose, the die 22 (Fig. .7) is provided with a recess to receive the boss 21 and with a curved wall 24; to give the brim portion the required shape. The punch 25 comprises a plunger :26. adaptcdto fit the curved 2.4-. of the die and carrying a centering projection 27 adapted to force the boss 21 into the recess 23, without, however, effecting any material change in the shape of said boss. The punch also comprises an inde pendently movable member 28 which descends in advance of the plunger 26 and yieldingly holds the peripheral part of the brim oi the blank during the initial portion of the operation so as to prevent the blank from crimping, creasing or buckling. As the punch 26 is moved to its lowest position, the blank is drawn by a cupping operation into the shape illustrated in dotted lines in Fig. 7. The blank is then removed from the die, and acted upon by another cupping punch and die which are generally similar to those shown in Fig. T, but are so shaped as to perfect the form of the shell or dome portion 10 of the blank and form the flange l3 on the periphery thereof, as shown in Fig. 8. The socket cap is then completed by cutting out the bottom of the boss 21, (thereby creating the hub 11), tapping the bore of the boss or hub with the threads 12, and forming the customary small tapped opening 29 in the wall of the hub.

It will be understood that intermediate the several operations above described, the blank will be annealed to soften the same, and permit further stretching of the metal without breaking, and that it will be subjected to the usual pickling operations for thoroughly cleansing the same. Furthermore, it will be evident that the total number of drawing or stamping operations may be m ried, as called for by conditions, and the sequence of certain operations ma likewise be varied without departing from the scope of the invention. Furthermore, so far as concerns the broad aspects of the process of making the drawn socket cap, it is not essential that the thick wall of the hub be form d by flowing or displacing the metal both in an inward direction and an outward direction relative to the center of the blank.

In Fig. 9, I have illustrated another step oi a somewhat modified method of forming the cap. According to this modification, I begin with a thinner blank oi? say. .050 gage, and form a substantially cylindrical. boss 30 directly thereon by means of a punch 31 and die 32. In this operation, the metal is flowed or displaced inwardly and downwardly, and also upwardly and outwardly around the projection 33 on the punch, substantially as previously described. The brim portion of the blank in this case only has to be flattened out to a slight extent, and therefore the periphery of said brim portion is confined in the manner shown, by an upright wall as. Although it might appear that by starting with a thinner blank, the process previously described could be somewhat shortened. the fact is that in carrying out the operation shown in Fig. 9, the comparatively large superficial area of the blank reduces to a considerable degree'the pressure per unit of area. The operation is less satisfactory, therefore, than that first described, according to which heavy pressure is distributed over a small blank area in forming the blank during the initial stages.

Various changes can be made in the form of the socket cap, and the method of producing same, without departing from the in vention as defined in the claims. Moreover it will be obvious that'the cap need not in all cases be used for the specific purpose stated.

I do not claim herein the improved socket cap per se as same forms the subject matter of my divisional application, Serial Number 14.71522, filed August 26, 1915.

What I claim is:

1. The method of making a socket cap, which comprises pressing the central portion of a disk-like blank into a boss of approximately the initial thickness of the blank at said central portion, swaging the peripheral portion of the blank to flatten the same, and drawing the metal of the flattened peripheral portion into the shape of a dome; substantially as described.

2. The method of making a socket cap, which comprises cupping the central portion of a diskdike blank to form said central portion into a boss, swaging the outer portion of the disklike blank to flatten the same, drawing the outer portion of the blank into the shape of a dome, and perforating and threading the central. boss to form a' hub; substantially as described.

3. The method of making a socket cap or similar article, which comprises thickening the metal of a disk-like blank in one Zone so as to produce a blank having a relatively thick central portion and a relatively thin outer portion, forming the thick central portion of the blank into a hub, and drawing the thin outer portion of the blank to form a dome or shell integral with said hub; substantially as described.

41. The method of making a one-piece sheet metal socket cap or similar article, which comprises thinning the peripheral portion of a disk-like blank so as to form a relatively thick central portion and shaping said central. portion into a hub, and drawing the outer thinner portion of the blank into a dome or shell; substantially as described.

The method of making a socket cap or similar article, which comprises the radial flowing oi. the metal of a blank to form a thick inner portion and a thin outer portion and cupping the respective portions to create a hub and a dome respectively.

6. In the method oi making a socket cap having a thin shell and a thick central hub thereon, cupping the central portion of the blank and displacing the metal radially to form a relatively thick hub.

7 The method of making a socket cap, having a thin shell and a thick central hub, which comprises displacing the metal of a disk-like blank radially by pressure to form an outer thin zoneand an inner thick zone, shaping the metal in the thin zone into a shell or dome, and shaping the metal in the thick zone into a hub; substantially as described.

S. In the method of making a socket cap, flattening out the peripheral portion. of a disk-like blank, to form a thin shell wall, and crowding metal radially inward from a zone remote from the center, to form a thick 'hub wall; substantially as described.

9. The method of making a socket cap or similar article, which comprisesoperating on a disk-like blank 01 substantially uniform initial thickness to create a blank having a thick central portion and a thin outer portion and cupping and shaping said portions to create a hub and dome respectively;

10. The steps in method of making a socket cap, which comprise thickening a certain zone of a disk-like blank and forming the thickened part into ahub; substantially as described.

11. The method of making a socket cap or similar article, which comprises displacing inwardly the metal in one zone of a disk-like blank, and displacing outwardly the metal in another zone, so as to form a thickened intermediate zone of metal on the blank; substantially as described. 7

12. The method of making a socket cap, which comprises flattening out the peripheral portion of a disk-like blank, crowding metal radially nearer the center of the blank,

toform a thickened portion, forming said thickened portion into a hub, and shaping the flattened peripheral portion into a domeinward, and displacing the central portion of the blank radially outward, forming a hub of the thickened part created by such displacement'of the metal, and forming the flattened peripheral portion of the blank into a dome; substantially as described.

15. The method of making a socket cap, having a thin-shell and a thick central hub integral therewith, which comprises displacing the metal of a disk-like blank radially to formjan outer thin zone and an inner thick zone, shaping the metal in the thin zone into a cup-like shellor dome, shaping the metal in the thick zone into a central boss, and perforating and threading the boss to create a finished hub on the dome or shell-substantially as described.

16. The method of making a sheet metal one-piece cap for electric light sockets, hav ing a thin shell and a thick central hub integral therewith, which comprises displacing the metal of a disk-like blank of sheet metal in a radial direction by pressure to form an outer thin zone and an inner thick zone in the blank, drawing the metal in the thin zone into a cup-like shell or dome, shaping the metal in the thick zone into cylindrical form to create a boss on the dome, and then perforating and threading the boss to form a finished hub; substantially as described.

17. The method of making a one-piece sheet metal cap for electric light sockets, having a thin dome and a thick central hub integral with the dome, which comprises subjecting the central portion of a disk-like blank to pressure so as to form a cylindrical boss, flattening out the peripheral portion of the blank to thin the same, and cupping the thin peripheral portion of the blank; substantially as described.

18. The method of making a one-piece socket cap, which includes pressing out a boss on the middle portion of a blank, and thereafter cupping the blank; substantially as described.

19. The method of making a one-piece socket cap, which includes forming a thick ened boss on the central portion of a disk- .like blank by radial displacement of the metal and thereafter cupping the outer portion oi the blank; substantially as described. 20. The method oi making a one-piece socket cap, which includes pressing out a cylindrical boss at the central portion of a disk-like blank, then cupping the blank to form a dome, and then perforating and threading the boss to form a finished hub on the dome; substantially as described.

21. The method of making a socket cap, which comprises displacing radially the metal of a disk-like blank and simultaneously shaping it to form a hub. V

22. The method of making a socket cap, which comprises displacing the metal of a disk radially and simultaneously forming it to create a thick hosson the disk, and hen shaping the peripheral portion.

23. The method of making a socket cap, which comprises cupping the central portion of a blank to form a boss and simultaneously flowing the metal into the side wall of the boss.

A. The method of making a socket cap,

which comprises cupping the central portion of a blank to form a boss and'simultaneously flowing the metal into the s1de wall ofthe boss tomake. such side wallIoi llO substantially uniform thickness from top to In Witness whereof, I have hereunto set bottom. my hand on the 8th day of February 1915.

25. Th8 methOd 0t Inaklng (L Socket Cap, W

which comprises stamping a fiat blank to 5 form a thick hub portion and a thin brim Witnesses:

portion and thereafter shaping" the brim W. R. HEOK, portion into a dome. L. M. ALLEN. 

